1. Field of the Invention
Embodiments relate to a diffuser plate, a backlight and a display having the same.
2. Description of the Related Art
Low power consumption and high luminance are important issues for liquid crystal display (LCD) devices, e.g., televisions, computer monitors, handheld devices, etc. Typically, LCD devices include a backlight unit, the characteristics of which may have a significant impact on power consumption and luminance.
Types of backlight units include a direct type backlight unit, in which lamps are disposed under a liquid crystal panel, and an edge type backlight unit, in which a light guide is installed under a liquid crystal panel and lamps are disposed at one end of the light guide. The direct type backlight unit has a high light utilization efficiency and a simple configuration, and is not limited to a particular size of display surface, thus being widely used in large-scale LCDs.
FIG. 15 illustrates an exploded perspective view of a structure of a general LCD.
With reference to FIG. 15, the LCD includes a liquid crystal panel 10 and a backlight unit 20. Liquid crystal cells are arranged in a matrix on the liquid crystal panel 10 such that light transmittance is adjusted by applying an electric field, and a polarizing plate 11 that changes light emitted from the backlight unit 20 to polarized light are respectively attached to upper and lower surfaces of the liquid crystal panel 10. The backlight unit 20 includes lamps 21 serving as light sources, a reflection plate 22, a diffuser plate 23, and optical sheets 24. A plurality of the lamps 21 may be provided to emit light.
The diffuser plate 23 serves to diffuse light emitted from the lamps 21 so as to prevent Becke's lines (bright lines) of the lamps 21 from being seen. Beads may be added into the diffuser plate 23 to diffuse light. A large amount of the beads may be necessary to prevent the images of the lamps 21 from being seen by the viewer.
The thickness of liquid crystal displays has been gradually thinned to provide a thin profile and light weight. Accordingly, reduced-thickness backlight units have been developed. As a result, the distance between light sources and a diffuser plate in the backlight unit has been reduced. When the distance between the light sources and the diffuser plate is reduced, a diffuser plate that relies on beads for diffusion has a limited ability to diffuse the light sources, such that images of the light sources, i.e., “hot spots” or brightly-lit regions, are generated at positions corresponding to the light sources. Accordingly, there is a need for a diffuser plate suitable for use in a thin backlight unit and capable of reducing or eliminating images of light sources in the backlight. Additionally, there is a need for a backlight unit that provides uniform brightness regardless of viewing angle.